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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Network Interface Layer (OSI Data Link Layer) Protocols            9  TCP/IP Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP)                 9  Point-to-Point Protocol (PPP)

PPP Authentication Protocols: Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) 1 PPP Link Quality Monitoring/Reporting (LQM/LQR)

PPP is the standard for data link layer connectivity over serial links because its core protocols provide a solid operational foundation, as we saw in the previous section. However, PPP's popularity is based not just on its highly capable link establishment and management features. It also has a number of very useful features that provide important security and performance benefits to network users.

In this section I describe the protocols that implement several of the most common "extra" features in PPP. I begin with a discussion of PPP link quality monitoring. I describe the sets of protocols used to configure and implement data compression and data encryption. I then discuss the PPP Multilink Protocol (MP, MLPPP), which allows PPP to bundle multiple low-speed links into a single high-speed link. I also cover the BAP and BACP protocols, which are used to manage the operation of Multilink PPP.

PPP Authentication Protocols: Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) 1 PPP Link Quality Monitoring/Reporting (LQM/LQR)